1. Field
The following description relates to an optical pickup device for optically recording information on, and detecting information from, a medium or a disk. Also, the following description relates to a method performed by an optical pickup device of controlling light directed to a medium having a multilayer structure, and an optical pickup device and an optical disk drive adopting the method.
2. Description of the Related Art
An optical pickup device using a 3-beam method obtains one main beam and two sub beams by using a diffraction element disposed between a beam splitter and a light source. A light-receiving sensor that converts a beam reflected from a medium into an electric signal includes a main beam region, to which the main beam reaches, and sub beam regions, to which the sub beams reach, at sides of the main beam region.
In such an optical pickup device using a 3-beam method, a 0th beam, i.e., a main beam, is used to generate a main push-pull (MPP) signal of a track error signal (TES), a focus error signal (FES), and a radio frequency (RF) signal, and −1st and +1st beams, i.e., sub beams, are used to generate a sub push-pull (SPP) signal of the TES.
Examples of a medium having a multilayer structure, for example, at least two recording layers, are a digital versatile disk (DVD) and a Blu-ray disk (BD). While recording information on, or reproducing information from, a medium having a multilayer structure, interference light may be generated in a layer of the medium other than a layer that is being accessed. The interference light and stray light may diffuse widely, and thus operate as optical noise in an SPP signal. As such, the interference light and stray light operating as optical noise in an SPP signal may interfere with controlling of tracking on the medium.
Such a phenomenon occurs in dual layer (DL) mediums and multilayer (ML) mediums.